Sequential PROPHET-600 - 7-1 OSCILLATOR A

If you suspect a data bus problem, try to pick out the lines with questionable levels.
For example. Figure 2-3 shows a normal data bus. The low voltages don't rise above
500 mV, while the high voltages are generally 4 to 5V, with occasional 3.5-V levels for
CMOS devices Note the solid ground line.
V: lV/div
H: 1.9 us/div
Figure 2-3
NORMAL DATA BUS
Figure 2-4 shows what the same bus line looks like when shorted to +5V by a failed
device (in this case simulated by a 50-Ohm resistor.) The malfunction is indicated
especially by the signals in the 1 to 3V range and by the lack of solid ground.
V: lV/div
H: 1 us/div
Figure 2-4
SHORTED DATA BUS
2-8 TM600A 7/83